A deadly 'Game of Thrones' theory about Jaime and Cersei could come true this season

Warning: Spoilers ahead for "Game of Thrones," including speculation of future events.

The "Game of Thrones" season six finale stunned viewers when Cersei Lannister not only pulled off one of the greatest character massacres in the series' history, but then proceeded to claim the Iron Throne after her last living child committed suicide. Cersei ruling King's Landing is frankly horrifying, but if this fan theory is correct, then her days are numbered.

In the books, Cersei's murder is prophesied by a witch. And not just any witch, but a woman who correctly predicts two other important details of Cersei's future. Some people believe this prophecy subtly names Jaime Lannister as the person destined to kill Cersei.

Jaime looked shocked when he arrived in King's Landing. HBO

We've seen Cersei's fortune teller in the show, back in the first episode of season five.

Season five opened with a flashback to young Cersei seeking out a fortune teller named Maggy the Frog. In both the books and show, Cersei is told she can ask three questions of the witch. For fans of the novels, this seemed like a pretty clear cut scene to adapt. However, there was a big omission from the show's version of Cersei and Maggy's conversation.

Young Cersei and her friend as seen in the opening of season five. HBO

Cersei's questions for Maggy

The first question and answer were almost word for word from a scene of the fourth book, "A Feast for Crows." Here's how the conversation played out on screen:

Cersei: I'm promised to the prince. When will we marry? Maggy: Never. You will wed the king. Cersei: But I will be queen? Maggy: Oh yes. You will be queen, for a time ... until there comes another, younger and more beautiful, to cast you down and take all that you hold dear.

Many fans of the books have analyzed the last line from Maggy over and over again.

Maggy the Frog is a fortune-telling witch. HBO

For a long time, the standing theory was that the "younger, more beautiful" person was another queen. Margaery Tyrell was a clear candidate and the most obvious choice. She was about to marry Tommen and become Queen of the Seven Kingdoms, and this means bad news for Cersei.

But the wording from Maggy is tricky, and it's never specified that this other figure is another queen or even in fact a woman. (Though some believe this could be Daenerys, Sansa, or even Brienne of Tarth.)

Back in the show's opening scene, Cersei moves on from this disconcerting answer, and asks her second question: "Will the king and I have children?" Maggy responds with: "The king will have twenty, you will have three." Cersei tried to interrupt, clearly confused.

Readers and viewers alike now understand that Cersei and the former king, Robert Baratheon, never conceived together; all of his children were bastards and all of hers were born from the incestuous relationship she has with her brother, Jamie Lannister.

Tommen and Jaime stand over Myrcella's dead body. Helen Sloan/HBO

Maggy continues, stating "Gold will be their crowns, and gold their shrouds," before devolving into hysterical laughter.

This line can be interpreted in a few different ways. The gold crowns could be literal crowns, since Joffrey and Tommen were both crowned king. Plus, in the books, there is a plot centered around women in Dorne crowning Myrcella queen. But it probably simply refers to their hair color: blonde, like their parents.

"Gold their shrouds" is more direct: all of Cersei's children will die. Joffrey and Myrcella were both been murdered, and each was shown in golden funeral garb. Tommen killed himself by jumping out of a window, and he was wearing a golden jacket.

In this moment of the show, book readers knew exactly what Maggy was going to say next. Or so they thought. Instead, the scene quickly ended, cutting to present-day Cersei on her way to her father's funeral.

Cersei in her mourning gown, headed to Tywin's funeral. HBO

She's clearly musing over how recent events seem to be playing out along Maggy's predictions. And here is where many book readers were left dismayed.

The book text has a third, and crucial, line in Maggy's answer.

The "valonqar" prophecy

In the books, Cersei is told one final and foreboding thing about her future. "And when your tears have drowned you, the valonqar shall wrap his hands about your pale white throat and choke the life from you," Maggy says.

This is huge in the realm of Cersei-centric theories. Not only does the text make it clear that her children are going to die before her, but it also predicts her murder at the hands of "the valonqar."

In the High Valyrian language of the east, "valonqar" means "little brother." Maggy is telling Cersei that her death will come at the hands of a younger brother.

Knowing that, all minds may jump to Tyrion, the youngest of the Lannister children. He's currently in exile after being persecuted unfairly by Cersei for the death of her son Joffrey. But, just as with Maggy's first prediction, there are alternate interpretations to this line.

Tyrion was wrongfully convicted of murdering his nephew Joffrey. Helen Sloan/courtesy of HBO

The case for Jaime Lannister

Jaime — Cersei's twin, lover, and father of her children — was the last to leave their mother's womb, making him younger than Cersei by mere minutes. He is technically another of her "little brothers." Could he turn on Cersei in the future, and strangle her to death?

Their relationship was tense in season five. Cersei loathed Jaime's missing hand, and therefore diminished fighting skills. Then he blundered by releasing Tyrion and consequentially allowing his father to be murdered. Jaime was also becoming impatient with Cersei's insistence on terrorizing Tyrion and her increasing paranoia. We have seen Jaime grow from the narcissistic "kingslayer" to a more compassionate and nuanced man.

Season six initially showed Jaime reverting back to being Cersei's number one man. Despite Myrcella's death, the twins seemed closer than ever. Jaime assured Cersei that nothing else in the world matters except them.

But all that changed in the season finale. Jaime has seemed increasingly angry and disappointed with Cersei in the episodes since the season six finale, even if it's only small moments that show his discomfort.

Cersei's choice to murder hundreds of people isn't sitting well with Jaime. HBO

He left King's Landing to represent House Lannister in the Riverlands, and by the time he returned Cersei had gone full Mad Queen. Tommen was Jaime's son, and Cersei effectively gave up on him the moment Tommen sided with the High Sparrow and denied her a trial by combat.

We know from the books that Jaime does eventually become disillusioned with Cersei. This is partially due to a major falling out he has with Tyrion, during which Jaime learns about Cersei's lack of faithfulness to their relationship.

But since the show left out that significant scene between Tyrion and Jaime, this final season six decision of Cersei's might be the new reason for Jaime finally breaking ties with his sister.

The abrupt end to the fortune-telling back in season five makes us wonder why show creators David Benioff and D.B. Weiss left out the "volanqar" prophecy. Are they planning on revisiting the flashback and finishing out the scene at some point or is it not as important as book readers thought, and not worth mentioning?

If it wasn't worth mentioning, perhaps that's because it sounded redundant and was already addressed in the first answer, where Cersei learns of "another, younger and more beautiful" who will cast her down. Could that individual be the same as the "valonqar"? As noted earlier, there is no gender associated with this younger and more beautiful enemy. Jaime Lannister, born moments after Cersei, is known for his devilish good looks across the kingdom. Jaime Lannister, whose character arc may lead him further and further away from the hateful and paranoid Cersei, could be her undoing.

Cersei seems steeled against Jaime's fury as she takes the Iron Throne. HBO

Jaime was forced to kill the Mad King Aerys years ago in order to protect the people of King's Landing. Cersei has set herself up to be anything but a benevolent ruler, and her use of wildfire creates a direct parallel between herself and the former Targaryen ruler. If Queen Cersei follows in the Mad King's footsteps, will Jaime feel morally obligated to intervene?

Tommen's death and Cersei fast rise to power on the season six finale seemed like the groundwork for a falling out in season seven. Cersei's rule in King's Landing might come to end more quickly than she anticipated, and Maggy the Frog will have the final word, after all.